PARAMETERS OF ECOLOGY AND SCALE INTEGRATE THE GRADIENT AND MOSAIC MODELS OF HYBRID ZONE STRUCTURE IN BOMBINA TOADS AND TRITURUS NEWTS

ABSTRACT

The spatial and ecological characteristics of two hybrid zones of amphibians are described. In two species of fire-bellied toads (genus Bombina) in central Europe, the location of the hybrid zone between them is determined by the parameters altitude and relief. In western France, the distribution of two hybridizing species of newts (genus Triturus) is described by the parameters relief and forestation. The toads fit the gradient model of hybrid zone structure, whereas the newts fit the mosaic model of hybrid zone structure. However, when the spatial scale of observation is varied, the distinction between the models fades and a continuum might exist between them.